The present invention relates to a disk cartridge such as a magnetic disk cartridge, an optical disk cartridge, or a magneto-optical disk cartridge, and more particularly to a disk cartridge in which an inclined portion of a resilient member is adapted to resiliently bring a part of a cleaning sheet into contact with the disk of the cartridge so as to clean the surface of the disk.
FIG. 9 is a bottom view of an upper case with a cleaning sheet attached thereto in a conventional magnetic disk cartridge. FIG. 10 is a top plan view of a lower case with the cleaning sheet attached thereto in the magnetic disk cartridge. FIG. 11 is an enlarged cross-sectional view illustrating a state where the upper and lower cases of the magnetic disk cartridge are subjected to ultrasonic welding. FIG. 12 is an enlarged cross-sectional view of a resilient member disposed in the magnetic disk cartridge.
The magnetic disk cartridge mainly comprises a cartridge case 1, a magnetic disk 2 (see FIG. 12) accommodated rotatably therein, and a shutter (not shown) supported slidably by the cartridge case 1 and adapted to open and close head insertion ports or apertures 5.
The cartridge case 1 comprises an upper case 1a and a lower case 1b which are formed of a hard synthetic resin, such as ABS resin. As shown in FIG. 10, an opening 4 in which a rotating and driving shaft is inserted is formed substantially in the center of the lower case 1b, and the head insertion port 5 having a rectangular shape is provided in the vicinity thereof. The upper case 1a is similarly provided with the head insertion port 5 (see FIG. 9).
A plurality of protrusions 3 arranged in parallel at predetermined positions and arcuate restricting ribs 6 for restricting the accommodation position of the magnetic disk 2 are provided on an inner surface of the upper case 1a. A cleaning sheet 7 made of, for instance, a non-woven fabric formed of a mixture of rayon fibers and polyester fibers, is placed in a space surrounded by the restricting ribs 6. Since the cleaning sheet 7 is thus placed, the protrusions 3 are covered with the cleaning sheet 7, and the peripheral portion of the cleaning sheet 7 is heat-bonded to the upper case 1a at a portion 9 by means of ultrasonic welding or a similar method.
As shown in FIGS. 10 and 12, a protruding support 10 and adhesion preventing protrusions 11 are provided on the inner surface of the lower case 1b and at a position substantially opposing the protrusions 3 of the upper case 1a. In addition, a proximal end portion 13 of a resilient member 12 formed by bending a plastic sheet into the form of a chevron is secured to the inner surface of the lower case 1b in the vicinity of the support 10 by a suitable means, such as bonding or welding. The distal end portion of the resilient member 12 is provided with an inclined portion 14 which projects in such a manner as to be inclined relative to the lower case 1b.
The lower case 1b is also provided with the restraining ribs 6 in the same way as the upper case 1a, and the cleaning sheet 7 is placed on the inner side thereof. Since the cleaning sheet 7 is thus placed, the resilient member 12 is covered, and most of the peripheral portion of the cleaning sheet 7 is welded or heat-bonded to the lower case 1b at the portion 9. However, a portion of the peripheral portion of the cleaning sheet 7 opposed to the opposite side ends of the resilient member 12 is not heat-bonded.
As shown in FIG. 9, bosses 15 are provided in the vicinity of the four corners of the upper case 1a, and, as shown in FIG. 10, cylindrical portions 16 into which the bosses 15 are inserted are provided in the vicinity of the four corners of the lower case 1b, respectively. As shown in FIG. 11, a portion 17, an allowance for welding is formed at the tip portion of each of the bosses 15, and the bosses 15 are respectively inserted into the cylindrical portions 16 with the portions 17, for fusion, facing downward. Subsequently, as ultrasonic energy is supplied to contacting portions of the boss 15 and the cylindrical portion 16, the portions 17 are melted, and the tip portions of the bosses 15 are thereby bonded to the inner bottom surfaces of the cylindrical portions 16.
If the disk cartridge is assembled by bonding together the upper case 1a and the lower case 1b as a unit, the cleaning sheet 7 on the side of the lower case 1b is partially lifted by the inclined portion 14 of the resilient member 12, as shown in FIG. 12, while a part of the cleaning sheet 7 in the upper case 1a opposed to the lifted portion is slightly pushed downwardly by the protrusions 3 provided on the upper case 1a. Consequently, the magnetic disk 2 is clamped lightly and resiliently by the upper and lower cleaning sheets 7. Then, as the magnetic disk 2 rotates, the surfaces of the disk are cleaned by the cleaning sheets 7.
In cases where the resilient member 12 and the cleaning sheets 7 are used to clean the magnetic disk 2, the highest lifted portion of the cleaning sheet 7, lifted by the resilient member (inclined portion 14), i.e., point C in FIG. 12, has the largest cleaning effect, and this point C (which is a straight line in a plane parallel to the disk 2) is referred to as the cleaning position in this specification or description.
As shown in FIG. 10, in a conventional disk cartridge, the aforementioned resilient member 12 and the like are disposed in such a manner that this cleaning point C is located in a range of from 90 to 120 degrees upstream of a center line X of the head insertion port 5 in the rotating direction of the disk.
With the conventional disk cartridge thus arranged, at the time when the disk cartridge is inserted into the recording and reproducing apparatus, no problem is experienced when the magnetic head is brought into pressure contact with the magnetic disk 2 after the front or leading portion of the disk surface cleaned at the above-described cleaning position C has passed under the magnetic head. However, there are cases when the magnetic head is brought into pressure contact with the disk surface which has not yet been cleaned before the aforementioned cleaned front or leading portion passes below the magnetic head. If dust or the like attaches to this portion of disk surface, the dust or the like is contacted with the disk surface by the colliding force of the magnetic head and consequently becomes attached more firmly thereto, making it impossible to wipe it off with the cleaning sheets 7 and resulting in a permanent error or damage.
In the case of the conventional disk cartridge, the cleaning position C is located substantially upstream of the head insertion port 5 (at a position about 90 to 120 degrees away from the center axis X of the head insertion port 5).
Meanwhile, because of the simplified structure of the recording and reproducing apparatus, a recently available arrangement is provided such that, after insertion of the disk cartridge, the magnetic head is brought into pressure contact with the magnetic disk 2 at a relatively early timing.
For that reason, if the cleaning position C is substantially separated from the head insertion port 5, it takes time until the cleaned front portion passes under the magnetic head, so that the magnetic head is brought into pressure contact with the magnetic disk 2 relatively early before the above described time, resulting in a disadvantage such as the one described above.
Thus, in the case of the magnetic disk cartridge, the above-described problem occurs since the magnetic head is directly brought into pressure contact with the uncleaned magnetic disk 2. However, even in the case of an optical disk cartridge in which the optical head does not contact the disk, it is preferable to make the cleaned front portion of the disk pass below the optical head before the optical head accesses or contacts the disk.
In addition, in the case of the conventional disk cartridge, in the state shown in FIG. 10 where it is midway in an assembly process, both portions of the cleaning sheet forward and rearward of the resilient member 12 are bonded in a state in which the cleaning sheet 7 is partially raised and stretched.
However, if the upper case 1a and the lower case 1b are bonded, as shown in FIG. 12, the resilient member 12 is pushed down by the protrusions 3 of the upper case 1a, so that a slacked portion is created in the cleaning sheet 7, which has been tight, and creases occur. Since these creases are formed on the resilient member 12 which would have the largest cleaning effect, it is impossible to demonstrate a sufficient cleaning effect. However, if the amount of slackening of the cleaning sheet 7 is large, the state of the cleaning sheet is such that it becomes entangled with the rotating magnetic disk 2, so that there is a drawback in that the required rotational torque of the magnetic disk 2 is increased.